Technical Field
The present invention relates to a light-emitting element, a light emission apparatus, an authentication apparatus, and an electronic machine.
Related Art
An organic electroluminescent element (a so-called organic EL element) is a light-emitting element having a structure where at least one light-emitting organic layer is interposed between an anode and a cathode. With such a light-emitting element, applying an electric field between the cathode and the anode causes electrons to be injected to the light emission layer from the cathode side and causes positive holes to be injected from the anode side; recoupling of the electrons and positive holes in the light emission layer generates excitons, and when the excitons return to the ground state, the energy content thereof is released as light.
One known form of such a light-emitting element emits light at a long wavelength region exceeding 700 nm (for example, see Japanese laid-open patent publication No. 2000-091073 and Japanese laid-open patent publication No. 2001-110570).
For example, in the light-emitting elements disclosed in Japanese laid-open patent publication No. 2000-091073 and Japanese laid-open patent publication No. 2001-110570, the light emission wavelength is lengthened by using, as a dopant of the light emission layer, a material in which the molecule has an amine that is an electron donor and nitrile group that is an electron acceptor as coexistent functional groups.
The use of a benzo-bis-thiadiazole-based compound as a light emission material of a light emission layer not containing a host material has also been reported (for example, see Chem. Asian J. 2010, 5, 1006-1029).
However, it has conventionally been impossible to achieve a high-efficiency and long-lasting element that emits light in the near-infrared region.
A high-efficiency and long-lasting light-emitting element that emits light perpendicular to the surface plane in the near-infrared region has also been desired as a biometric authentication light source for using biometric information such as, for example, the veins, fingerprints, or the like to authentic an individual.